Re: Re: [Qemu-devel] Bug with TARGET_PHYS_ADDR_SPACE_BITS

[Alan Pevec]

Anthony Liguori wrote:
> Chris Lalancette wrote:
> > Hello,
> >      oVirt is currently using straight x86_64 qemu emulation for 
> > certain parts
> > of the architecture (we mostly use KVM, but need to use full emulation 
> > for a
> > couple of parts).  We recently upgraded our userspace package to 
> > kvm-72, but
> > found that we could not PXE boot guests when we were doing full 
> > emulation (under
> > kvm, we could PXE boot just fine).  We also tried using qemu SVN tip, 
> > with
> > similar results.  We ended up doing a bisect, and tracked down the 
> > problem to
> > this commit (from the kvm repo, but pulled from qemu):
> >
> > http://git.kernel.org/?p=linux/kernel/git/amit/kvm-userspace.git;a=commit;h=468f7507339a5236bff8ab339eb0c1b019a95fda 
> >
> >
> > The important changes in there in terms of this bug revolves around
> > TARGET_PHYS_ADDR_SPACE_BITS in exec.c.  If I change that back to 32 
> > (what it was
> > before this patch for x86_64), the PXE boot succeeds.  Also, if I remove
> > TARGET_PHYS_ADDR_SPACE_BITS > 32 conditional code in 
> > phys_page_find_alloc(), but
> > leave TARGET_PHYS_ADDR_SPACE_BITS as 42, the PXE boot also works.  I 
> > can't claim
> > to understand the conditional code I've compiled out, so I'm not sure 
> > where the
> > bug would be.  Does anyone have an idea what the problem might be?
> >   
>
> Right now, the code just can't handle TARGET_PHYS_ADDR_SPACES_BITS > 
> 32.  This may help you:

I applied that to qemu svn trunk but still get the same tripple fault w/ 
pxelinux (syslinux-3.61-2.fc9)
qemu: fatal: triple fault
EAX=0f8ef0a8 EBX=f0711ae0 ECX=f07b0244 EDX=f07b026e
ESI=f0711adc EDI=00000001 EBP=0f8ee990 ESP=f07b0016
EIP=00000717 EFL=00000002 [-------] CPL=0 II=0 A20=1 SMM=0 HLT=0
ES =0010 0f8ee990 ffffffff 0fcf938e
CS =0008 0f8ee990 ffffffff 0fcf9f8e
SS =0010 0f8ee990 ffffffff 0fcf938e
DS =0010 0f8ee990 ffffffff 0fcf938e
FS =0010 0f8ee990 ffffffff 0fcf938e
GS =0010 0f8ee990 ffffffff 0fcf938e
LDT=0000 00000000 0000ffff 00008200
TR =0000 00000000 0000ffff 00008b00
GDT=     0f8f6ed0 00000037
IDT=     00000000 000003ff
CR0=00000011 CR2=00000000 CR3=00000000 CR4=00000000
CCS=0f8ee990 CCD=0f8efa5c CCO=ADDL    
FCW=037f FSW=0000 [ST=0] FTW=00 MXCSR=00001f80
FPR0=0000000000000000 0000 FPR1=0000000000000000 0000
FPR2=0000000000000000 0000 FPR3=0000000000000000 0000
FPR4=0000000000000000 0000 FPR5=0000000000000000 0000
FPR6=0000000000000000 0000 FPR7=0000000000000000 0000
XMM00=00000000000000000000000000000000 XMM01=00000000000000000000000000000000
XMM02=00000000000000000000000000000000 XMM03=00000000000000000000000000000000
XMM04=00000000000000000000000000000000 XMM05=00000000000000000000000000000000
XMM06=00000000000000000000000000000000 XMM07=00000000000000000000000000000000